Although I devotd my comments to several drawbacks I can see in introducing an audit into a project I can appreciate a list of benefits this act has, as written here and elsewhere. I agree that they can be objective, then a new question is raised:
Is there a commonly agreed objective way of doing things in this world of project management?
This area of management is still under research and changes each term. What was best practice yesterday turns to be a damaging practice today, when new practices arise.
I really appreciate the benefit a PM can have by adding an independent viewer of the project to his team. I can hardly see this benefit when the same person/function is appointed as an auditor.